[Patch net-next 03/13] tcp: introduce tracepoint trace_tcp_transmit_skb()

[Cong Wang <xiyou.wangcong@gmail.com>]

From: Qitao Xu <qitao.xu@bytedance.com>

Tracepoint trace_tcp_transmit_skb() is introduced to trace skb
at the exit of TCP layer on TX side.

Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Qitao Xu <qitao.xu@bytedance.com>
---
 include/trace/events/tcp.h | 11 +++++++++--
 net/ipv4/tcp_output.c      |  8 +++++++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 521059d8dc0a..6147528d93ba 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -88,11 +88,18 @@ DECLARE_EVENT_CLASS(tcp_event_sk_skb,
 			      sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
 	),
 
-	TP_printk("family=%s sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c state=%s",
+	TP_printk("family=%s sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c state=%s skbaddr=%px",
 		  show_family_name(__entry->family),
 		  __entry->sport, __entry->dport, __entry->saddr, __entry->daddr,
 		  __entry->saddr_v6, __entry->daddr_v6,
-		  show_tcp_state_name(__entry->state))
+		  show_tcp_state_name(__entry->state), __entry->skbaddr)
+);
+
+DEFINE_EVENT(tcp_event_sk_skb, tcp_transmit_skb,
+
+	TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+
+	TP_ARGS(sk, skb)
 );
 
 DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 29553fce8502..628b28332851 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1420,8 +1420,14 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 			    gfp_t gfp_mask)
 {
-	return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask,
+	int ret;
+
+	ret = __tcp_transmit_skb(sk, skb, clone_it, gfp_mask,
 				  tcp_sk(sk)->rcv_nxt);
+	if (!ret)
+		trace_tcp_transmit_skb(sk, skb);
+	return ret;
+
 }
 
 /* This routine just queues the buffer for sending.
-- 
2.27.0